Service providers typically offer numerous voice and data services to end users of mobile devices. Some examples of voice services are voice calls, call forwarding, call waiting, etc. Some examples of data services are Internet access, streaming audio, streaming video, online gaming, Internet Protocol television (IP-TV), etc.
The first types of wireless or mobile networks that were introduced by service providers were First Generation (1G) and Second Generation (2G) networks. 1G networks provided voice services via analog signals, and then evolved into 2G networks that provided voice services via digital signals. Mobile communications then evolved into 3G (including 2.5G) networks that provided both voice services and data services. For example, 3G networks are able to provide wireless voice telephony, as well as data services such as Internet access, video calls, mobile TV, etc. Some of the 3G networks implemented by service providers were Universal Mobile Telecommunications System (UMTS) networks, Enhanced Voice Data Optimized (EV-DO) networks, General Packet Radio Service (GPRS) networks, etc. Service providers are now beginning to migrate their networks toward Fourth Generation (4G) technologies over Packet-Switched (PS) networks. 4G networks are essentially enhancements to 3G networks in terms of data speeds. For example, a 3G network can provide data speeds of about 3.5 Mbit/sec. According to the International Telecommunication Union (ITU), a 4G network can provide data speeds of 100 Mbit/sec. One example of a 4G network is a Long Term Evolution (LTE) network.
When a mobile device initiates a session over a PS network (e.g., an IP Connectivity Access Network (IP-CAN) session), the session request from the mobile device includes a description of the requested service (e.g., online gaming, IP-TV, etc). The PS network authenticates the mobile device and determines which services the mobile device is authorized to receive. If the requested service is authorized, then the PS network reserves a bearer path (e.g., an IP-CAN bearer) of a defined capacity, delay, and bit error rate over a selected Packet Data Network (PDN). A flow of packets may then begin for the service, which is referred to as a packet flow, a data flow, or a service data flow (SDF) over the PDN.
The service providers use offline and online billing functions to keep track of the charges incurred by each device for using the various services. The 3GPP/3GPP2 standards groups have defined a set of specifications that may be used to implement online charging systems and offline charging systems to cover charging in the various network domains (e.g., a circuit-switched domain, a packet-switched domain, and/or a wireless domain), IP multimedia subsystems (IMS), and emerging 3G/OMA application services.
Online charging is generally defined as a charging mechanism where charging information can affect, in real-time, the service rendered, and therefore a direct interaction of the charging mechanism with session/service control is needed. In online charging, usage is pre-approved and consumption follows the approval such that when the pre-approved quota (in terms of time or bytes in the uplink/downlink direction, etc.) is nearing exhaustion, a subsequent quota pre-approval is requested for the subscriber by a network element. Each time a quota is requested, the online charging system adjusts the subscriber balance in line with the service being accessed by the subscriber, which may be determined by the rating engine based on a number of parameters. However, in each case, authorization for the network resource usage is obtained by the network prior to the actual resource usage. The network elements in a communication network include Charging Trigger Functions (CTF). For online charging, the CTF triggers on charging events, collects charging information pertaining to the charging events, and assembles the charging information into matching charging events. The CTF then transmits credit request messages to the Online Charging System (OCS) to obtain authorization for the charging event/network resource usage requested by the user. The CTF delays the actual resource availability and usage until permission has been granted by the OCS. When a granted quota of service units is obtained from the OCS, the CTF performs budget control during the resource usage. The CTF enforces termination of the end user's resource usage when permission by the OCS is not granted or expires.
Over a PS network, a session for an end user may comprise multiple bearers and each bearer may include multiple service data flows for services. Each service may be charged independently, which may result in a large number of credit requests being sent to the OCS. The OCS can become overwhelmed with all of the credit requests.